Compared to the rest of the San Diego market, the National City submarket has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 5 listings have been made available, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 240% of the available leases in the National City are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
Even though the median size is 3,010 sqft, there are still 0 new listings below 2,000 sqft. Most properties in this market are close to 2 floors. Most buildings in this area were built in 1974 and are Class B.